Costco (a chain in N. America; I don't know where the OP is located) sells 4-in-a-blister-pack 2gb San Disk SD cards for around thirty bucks. Buy three packs for a total of 12 cards. Get a card wallet and then number the cards. As you fill each card, put it back in the wallet with the number side facing outward through the little glassine window. I don't know anything about the file size of the GF-1 but simple math should take care of the shots-per-card question. Think of a card as a "roll" and, depending on how much you shoot, you should be covered.
I totally agree with the multiple-card approach. Don't worry about the speed of the card - unless you are burst-shooting - in which case it may very well be the choke point (smaller cameras usually don't have the buffer capacity) - otherwise it's only really a factor in downloading to the computer - something which is easily interlarded with other activities. The only need for high-speed cards is if you are working on a deadline and you have an assistant or runner, in which case you will be using multiple cards anyway.
As an example, I shoot 8 gb 233x CF cards on a D3 - a 12mp camera. Using the RAW+JPEG FINE storage option I get about 250 pairs (RAW+JPEG of the same image) on each card. RAW-only gets me just under four hundred. JPEG fine gets me 700-ish. I know that it's a bit "apples and oranges" but knowing how big a file you see in RAW and awareness of your shooting habits will help. I also use a D40 and a G9 - both cameras use SD cards - I have a wallet full of Ultra II cards and they perform just fine.
Enjoy your trip!